Although Hank is retired, he is an excellent handyman and often works part time on small projects for neighbors and friends. Last week his neighbor, Mike, offered to pay Hank $1,100 for minor repairs to his house. Hank completed the repairs in December of this year. Hank uses the cash method of accounting and is a calendar-year taxpayer. Compute Hanks gross income for this year from each of the following alternative transactions:

a. Mike paid Hank $400 in cash in December of this year and promised to pay the remaining $700 with interest in three months